core/firmware: gchelper.s moved to different directory

core/SConscript.firmware

@@ -172,12 +172,12 @@ SOURCE_MICROPYTHON = [
     'vendor/micropython/extmod/utime_mphal.c',
     'vendor/micropython/lib/embed/abort_.c',
     'vendor/micropython/lib/mp-readline/readline.c',
+    'vendor/micropython/lib/utils/gchelper_m3.s',
     'vendor/micropython/lib/utils/interrupt_char.c',
     'vendor/micropython/lib/utils/printf.c',
     'vendor/micropython/lib/utils/pyexec.c',
     'vendor/micropython/lib/utils/stdout_helpers.c',
     'vendor/micropython/ports/stm32/gccollect.c',
-    'vendor/micropython/ports/stm32/gchelper.s',
     'vendor/micropython/ports/stm32/pendsv.c',
     'vendor/micropython/py/argcheck.c',
     'vendor/micropython/py/asmarm.c',